Conventionally, there is known a displacement amount monitoring electrode structure constituting an angular speed sensor, for monitoring the displacement amount of a detection mass to drive and oscillate the detection mass at a constant target amplitude (see, for example, Patent Document 1). The displacement amount monitoring electrode includes a comb-teeth like fixed electrode and a comb-teeth like movable electrode. The fixed electrode includes a base part and electrode fingers, which are extending from the base part in a predetermined axis direction parallel to the substrate, and which are fixed to the substrate. The movable electrode includes a base part and electrode fingers, which are extending from the base part in a predetermined axis direction parallel to the substrate, and which can be displaced with respect to the substrate in a predetermined axis direction. In this displacement amount monitoring electrode, when the movable electrode is displaced with respect to the substrate in a predetermined axis direction, the capacitance between the fixed electrode and the movable electrode changes. In this case, the change amount of the capacitance corresponds to the displacement amount of the movable electrode. Based on this change amount of the capacitance, the displacement amount (amplitude) of the detection mass is monitored, and the detection mass is controlled so as to be driven at a target amplitude.
[Patent Document 1] Japanese Laid-open Patent Publication No. 2008-170455